Topic Contents

Fever or Chills, Age 12 and Older

Discusses fevers in those age 12 and older. Includes info on temperatures considered normal, mild fever, or high fever. Covers causes of fever and offers home treatment tips. Includes interactive tool to help you decide when to see a doctor.

Fever or Chills, Age 12 and Older

Topic Overview

Fever is the body's normal and healthy
reaction to infection and other illnesses, both minor and serious. It helps the
body fight infection. Fever is a symptom, not a disease. In most cases, having
a fever means you have a minor illness. When you have a fever, your other
symptoms will help you determine how serious your illness is.

Temperatures in this topic are oral temperatures. Oral
temperatures are usually taken in older children and adults. To convert a temperature from one method (such as the ear) to another, use the Interactive Tool: How Do Temperatures Compare?

Normal body temperature

Most people have an average
body temperature of about
37 °C (98.6 °F), measured orally
(a thermometer is placed under the tongue). Your temperature may be as low as
36.3 °C (97.4 °F) in the morning
or as high as 37.6 °C (99.6 °F)
in the late afternoon. Your temperature may go up when you exercise, wear too
many clothes, take a hot bath, or are exposed to hot weather.

Fever temperatures

A fever is a high body
temperature. A temperature of up to
38.9 °C (102 °F) can be helpful
because it helps the body fight infection. Most healthy children and adults can
tolerate a fever as high as
39.4 °C (103 °F) to
40 °C (104 °F) for short periods
of time without problems. Children tend to have higher fevers than
adults.

The degree of fever may not show how serious the
illness is. With a minor illness, such as a cold, you may have a temperature,
while a very serious infection may cause little or no fever. It is important to
look for and evaluate other symptoms along with the fever.

If you
are not able to measure your temperature with a thermometer, you need to
look for other symptoms of illness. A fever without other symptoms that lasts 3
to 4 days, comes and goes, and gradually reduces over time is usually not a
cause for concern. When you have a fever, you may feel tired, lack energy, and
not eat as much as usual. High fevers are not comfortable, but they rarely
cause serious problems.

Oral temperature taken after smoking or
drinking a hot fluid may give you a false high temperature reading. After
drinking or eating cold foods or fluids, an oral temperature may be falsely
low. For information on how to take an
accurate temperature, see the topic
Body Temperature.

Causes of fever

Travel
outside your native country can expose you to other diseases. Fevers that begin
after travel in other countries need to be evaluated by your doctor.

Fever and respiratory symptoms are hard to
evaluate during the flu season. A fever of
38.9 °C (102 °F) or higher for 3
to 4 days is common with the flu. For more information, see the topic
Respiratory Problems, Age 12 and Older.

Recurrent fevers are those that occur 3 or more times within 6 months and
are at least 7 days apart. Each new viral infection may cause a fever. It may
seem that a fever is ongoing, but if 48 hours pass between fevers, then the
fever is recurring. If you have frequent or recurrent fevers, it may be a
symptom of a more serious problem. Talk to your doctor about your
fevers.

Treating a fever

In most cases, the illness that
caused the fever will clear up in a few days. You usually can treat the fever
at home if you are in good health and do not have any medical problems or
significant symptoms with the fever. Make sure that you are taking enough foods
and fluids and urinating in normal amounts.

Low body temperature

An abnormally low body temperature (hypothermia) can be serious, even life-threatening. Low body temperature may occur from cold exposure, shock, alcohol or drug use, or certain metabolic disorders, such as diabetes or hypothyroidism. A low body temperature may also be present with an infection, particularly in newborns, older adults, or people who are frail. An overwhelming infection, such as sepsis, may also cause an abnormally low body temperature.

Think about whether the fever started soon after you began using a new medicine or a higher dose of a medicine.

Yes

Medicine may be causing the fever

No

Medicine may be causing the fever

Infection Symptoms, Multiple Types of Infection

Fever can be a symptom of almost any type of infection.
Symptoms of a more serious infection may include the
following:

Skin infection: Pain,
redness, or pus

Joint infection: Severe
pain, redness, or warmth in or around a joint

Bladder infection: Burning when you urinate, and a frequent
need to urinate without being able to pass much urine

Kidney infection: Pain in the flank, which is either side of
the back just below the rib cage

Abdominal infection: Belly pain

Difficulty Breathing Severity, Adult or Older Child

Severe trouble breathing means:

You cannot talk at all.

You have to
work very hard to breathe.

You feel like you can't get enough
air.

You do not feel alert or cannot think clearly.

Moderate trouble breathing means:

It's hard to talk in full
sentences.

It's hard to breathe with activity.

Mild trouble breathing means:

You feel a little out of breath but can still talk.

It's becoming hard to breathe with activity.

Pain Severity, Adult or Child (Not Baby)

Pain in adults and older children

Severe pain (8 to 10): The pain
is so bad that you can't stand it for more than a few hours, can't sleep, and
can't do anything else except focus on the pain.

Moderate pain (5 to 7): The pain is bad enough to disrupt your
normal activities and your sleep, but you can tolerate it for hours or days.
Moderate can also mean pain that comes and goes even if it's severe when it's
there.

Mild pain (1 to 4): You notice the pain,
but it is not bad enough to disrupt your sleep or activities.

Petechiae and Purpura

Sudden tiny red or purple spots or
sudden bruising may be early symptoms of a serious
illness or bleeding problem. There are two types.

Petechiae (say "puh-TEE-kee-eye"):

Are tiny, flat red or purple spots in the skin or
the lining of the mouth.

Do not turn white when you press on
them.

Range from the size of a pinpoint to the size of a small pea and do not itch or cause pain.

May spread over a large area of the body within a few hours.

Are different than tiny, flat red spots or birthmarks that are
present all the time.

Purpura (say "PURR-pyuh-ruh" or “PURR-puh-ruh”):

Is sudden, severe bruising that occurs for no clear
reason.

May be in one area or all over.

Is different
than the bruising that happens after you bump into something.

Fever Ranges, 12 and Older

Temperature varies a little depending on how you measure it.
For adults and children age 12 and older, these are the ranges for high,
moderate, and mild, according to how you took the temperature.

Oral (by mouth) temperature

High:
40 °C (104 °F) and
higher

Moderate:
38 °C (100.4 °F ) to
39.9 °C (103.9 °F )

Mild:
37.9 °C (100.3 °F) and
lower

Ear or rectal temperature

High:
40.6 °C (105 °F) and
higher

Moderate:
38.6 °C (101.4 °F) to
40.5 °C (104.9 °F)

Mild:
38.5 °C (101.3 °F) and
lower

Armpit (axillary) temperature

High: 39.5°C (103°F) and higher

Moderate:
37.4 °C (99.4 °F) to
39.4 °C (102.9 °F)

Mild: 37.3°C (99.3°F) and lower

Impaired Immune System, Adult

Certain health conditions and medicines weaken the immune system's ability to fight off infection and
illness. Some examples in adults are:

Diseases such as diabetes, cancer, heart disease,
and HIV/AIDS.

Long-term alcohol and drug
problems.

Steroid medicines, which may be used to treat a variety
of conditions.

Chemotherapy and radiation therapy for
cancer.

Other medicines used to treat autoimmune
disease.

Medicines taken after organ transplant.

Not
having a spleen.

Fever Estimates, 12 and Older

If you're not sure if a fever is high, moderate, or mild,
think about these issues:

With a high fever:

You feel very hot.

It is likely one of
the highest fevers you've ever had. High fevers are not that common, especially
in adults.

With a moderate fever:

You feel warm or hot.

You know you have
a fever.

With a mild fever:

You may feel a little warm.

You think
you might have a fever, but you're not sure.

Epiglottitis

Sudden drooling and trouble swallowing can be signs of a
serious problem called epiglottitis. This problem can
happen at any age.

The epiglottis is a flap of tissue at the back
of the throat that you can't see when you look in the mouth. When you swallow, it closes to keep food and fluids out of the
tube (trachea) that leads to the lungs. If the epiglottis becomes inflamed or
infected, it can swell and quickly block the airway. This makes it very hard to
breathe.

The symptoms start suddenly. A person with epiglottitis
is likely to seem very sick, have a fever, drool, and have trouble breathing,
swallowing, and making sounds. In the case of a child, you may notice the child
trying to sit up and lean forward with his or her jaw forward, because it's
easier to breathe in this position.

Difficulty Breathing Severity, Baby or Young Child

Severe trouble breathing means:

The child cannot eat or talk because he or she is
breathing so hard.

The child's nostrils are flaring and the belly
is moving in and out with every breath.

The child seems to be
tiring out.

The child seems very sleepy or confused.

Moderate trouble breathing means:

The child is breathing a lot faster than
usual.

The child has to take breaks from eating or talking to
breathe.

The nostrils flare or the belly moves in and out at times
when the child breathes.

Mild trouble breathing means:

The child is breathing a little faster than usual.

The child seems a little out of breath but can still eat or talk.

Symptoms of difficulty breathing can range from mild to severe. For example:

You may feel a little out of breath but still be able to talk (mild difficulty breathing), or you may be so out of breath that you cannot talk at all (severe difficulty breathing).

It may be getting hard to breathe with activity (mild difficulty breathing), or you may have to work very hard to breathe even when you’re at rest (severe difficulty breathing).

Dehydration Severity, Adult or Older Child

Severe dehydration means:

Your mouth and eyes may be extremely
dry.

You may pass little or no urine for 12 or more
hours.

You may not feel alert or be able to think
clearly.

You may be too weak or dizzy to stand.

You may
pass out.

Moderate dehydration means:

You may be a lot more thirsty than
usual.

Your mouth and eyes may be drier than usual.

You may
pass little or no urine for 8 or more hours.

You may feel dizzy
when you stand or sit up.

Mild dehydration means:

You may be more thirsty than usual.

You may pass less urine than usual.

Dehydration (General)

You can get dehydrated when
you lose a lot of fluids because of problems like vomiting or fever.

Symptoms of dehydration can range from mild to severe. For
example:

You may feel tired and edgy (mild dehydration), or
you may feel weak, not alert, and not able to think clearly (severe
dehydration).

You may pass less urine than usual (mild
dehydration), or you may not be passing urine at all (severe
dehydration).

Try Home Treatment

You have answered all the questions. Based on your answers, you may be
able to take care of this problem at home.

Try home treatment to relieve the
symptoms.

Call your doctor if symptoms get worse or you have any
concerns (for example, if symptoms are not getting better as you would expect).
You may need care sooner.

Home Treatment

In the early stages, you may be
able to correct
mild to moderate dehydration with home treatment
measures. It is important to control fluid losses and replace lost
fluids.

Adults and children age 12 and older

If you become
mildly to moderately dehydrated while working outside or exercising:

Stop your activity and rest.

Get
out of direct sunlight and lie down in a cool spot, such as in the shade or an
air-conditioned area.

Prop up your feet.

Take off any
extra clothes.

Drink a rehydration drink, water, juice, or sports
drink to replace fluids and minerals. Drink 2 L (2 qt) of cool liquids over
the next 2 to 4 hours. You should drink at least 10 glasses of liquid a day to
replace lost fluids. You can make an inexpensive rehydration drink at home. But
do not give this homemade drink to children younger than 12. Measure all ingredients precisely. Small variations can make the
drink less effective or even harmful. Mix the following:

1 L (1 quart ) purified water

2.5 mL (½ teaspoon) salt

30 mL (6 teaspoons) sugar

Rest and take it easy for 24 hours, and continue to drink a
lot of fluids. Although you will probably start feeling better within just a
few hours, it may take as long as a day and a half to completely replace the
fluid that you lost.

Many people find that taking a lukewarm [27 °C (80 °F) to
32 °C (90 °F)]
shower or bath makes
them feel better when they have a fever. Do not try to take a shower if you are
dizzy or unsteady on your feet. Increase the water temperature if you start to
shiver. Shivering is a sign that your body is trying to raise its temperature.
Do not use rubbing alcohol, ice, or cold water to cool
your body.

Dress lightly when you have a fever. This will help
your body cool down. Wear light pyjamas or a light undershirt. Do not wear very
warm clothing or use heavy bed covers. Keep room temperature at
21 °C (70 °F)
or lower.

If you are not able to measure your temperature, you
need to look for other symptoms of illness every hour while you have a fever
and follow home treatment measures.

Aspirin (also a non-steroidal
anti-inflammatory drug), such as Bayer or Bufferin

Talk to your child's doctor before switching back and
forth between doses of acetaminophen and ibuprofen. When you switch between two
medicines, there is a chance your child will get too much medicine.

Safety tips

Be sure to follow these
safety tips when you use a non-prescription medicine:

Carefully read and follow all directions
on the medicine bottle and box.

Symptoms to watch for during home treatment

You have
signs of dehydration and you are unable to drink
enough to replace lost fluids. Signs of dehydration include being thirstier than usual and having darker urine than usual.

Other symptoms develop, such as pain in one area of the body,
shortness of breath, or urinary symptoms.

Symptoms become more severe or frequent.

Prevention

The best way to prevent fevers is to reduce
your exposure to infectious diseases.
Handwashing is the single most important prevention
measure for people of all ages.

Immunizations can reduce the risk for fever-related illnesses, such as the flu. Although no vaccine is 100% effective, most routine immunizations are effective for 85% to 95% of the people who receive them. For more information, see the topic Immunizations.

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